Leak indicator



April 28, 1942. G. WIEMER LEAK INDICATOR Filed July 27, 1940 INVEN TOR, Q/s/ W/w/ 5v ATTORNEY Patented Apr. 28, 1942 UNITED STATES FATE. T QFFICE LEAK INDICATOR Gustav Wiemer, Los Angeles, Calif.

Application July 27, 1940, Serial No. 347,895

4 Claims.

a likelihood that the leak remains undetected 1 until there is a dangerous accumulation.

It is one of the objects of this invention to make it possible to detect leaks in an expeditious manner.

It is another object of this invention whereby slow leaks may be detected by viewing the movement of a liquid level in a glass gauge tube.

It is still another object of this invention to provide an improved and simplified apparatus for detecting leaks.

This invention possesses many other advantages, and has other objects which may be made more easily apparent from a consideration of one embodiment of the invention. For this purpose there is shown a form in the drawing accom panying and forming part of the present specification. This form will now be described in detail, illustrating the general principles of the invention; but it is to be understood that this detailed description is not to be taken in a limiting sense, since the scope of this invention is best'defined by the appended claims.

Referring to the drawing:

Figure 1 is a side elevation of a system to be tested by a leak detector incorporating the invention, a portion of the leak detector being in section;

Fig. 2 is a front elevation of a leak detector;

Fig. 3 is a sectional view taken along plane 3-3 of Fig. 1; and

Fig. 4 is a longitudinal sectional view of the leak detector shown in the process of obtaining leak indications.

In the present instance, a system of connected pipes I is illustrated in Fig. 1 as representative of a system to be tested. These pipes may be water or gas pipes or the like. leading to appropriate outlets. The system, after it is ready for testing, is arranged to be connected to a source of compressed air, such as an air hose, for placing the system under gas pressure. When testing the system, all of the outlets are closed and compressed air is allowed to flow into the system.

Slow leaks issuing from the system are difiicult to detect by ordinary pressure gauge meth-- ods. By the aid of the leak detector 3 adapted to be placed in fluid pressure relationship with the system I, these slow leaks are readily perceptible.

The leak detector 3 has an open body or frame 4-that may readily be made as a casting,

and formed with spaced arms 30 (Fig. 2) that define an open space. At the upper end of the frame 4, there is formed a closed upper chamber 5 appropriately confined by Walls of the frame 4. This upper frame 5 is entirely closed except for a downwardly extending port 6.. This port 6 is shown as formed in the bottom wall of the chamber 5. A glass capillary tube 1 having a small bore 8 is placed at its upper end into communication with the port 6. A rubber or other yielding gasket washer 9 may be interposed between the lower wall of chamber 5 and the upper edge of the tube 1 in order to maintain a fluid tight seal.

The arrangement is such that the lower end of the tube 8 may be placed into fluid conducting relationship with the system I under test. The pressure exerted by the compressed air in the system I in the bore 8 of the tube I acts upon the lower end of a liquid piston, the upper end of which is exposed in the chamber 5. The lower level of the liquid piston, when the device is in operation, is observed in tube I, and a lowering of this level is indicative of a leak.

The manner in which the liquid piston is positioned to effect these results will be described hereinafter. For the present, the structure of the frame 4 making it possible to connect the lower end of the tube 1 to the system I will be described.

The frame 4 carries at its lower end a down wardly extending hollow boss III. This boss ID has an internally threaded opening at the bottom thereof, which is adapted to be closed by a correspondingly threaded cap or cover II. A sealing gasket I2 may be interposed between the flange of the cover II and the lower edge of the boss III.

The upper end of the boss II] is shown as formed integrally with the bottom wall I3 of the frame 4. This end likewise has an internally threaded aperture adapted to be closed by a plug I4. Interposed between the top of the plug I4 and the bottom of the glass tube I is a rubber or other yielding sealing washer I5. The plug I4 furthermore carries a downwardly extending tube I6 in communication with the bore 8 of the tube 1. This tube may be forced into an appropriate aperture in plug I4. Tube It extends almost to the bottom of the chamber II formed within the boss II]. By appropriate manipulation of the plug I4 within the threads in boss III, the glass tube "I can be appropriatelyclamped and sealed in the upright position illustrated in Figs. 1 and 4.

The chamber I1, defined by the cover II and the plug I4, is adapted to hold a body of liquid I8. This body of liquid I8 may be drained, if

required, through an opening in the bottom of the cover I I normally closed by screw plug I9.

The boss l has a side extension 20 which is exteriorly threaded to receive any appropriate fitting 2| communicating with the system I. In the extension 2| there is fixed a hollow tube 23 conducting fluid pressure into the chamber ll. This tube 23 as shown most clearly in Figs. 1,

3 and 4 extends a considerable distance beyond the inner wall of the chamber ll. In this way inversion of the leak detector 3 or tilting thereof will not result in the flow of any of the liquid .IB into the fitting 2|.

The body of liquid i8 is sufficient to keep the bottom ofthe tube 10 covered while the liquid 18 is in this lower, chamber. 'The volume'of indicated at 24. Accordingly a comparatively :srnall body of' liquid i8 is sufficient to bring the jlevelbf the liquid normally considerably above 'thebottom of the tube It when the leak indizcator isnot'in use.

I Thebore 8 of theg'las's tube l is visible to an observerjsince' it extends from top to bottom of thoopenrrame" l This bore ispurpo'sely made quite smalliii diameter, of the order of .080 inch. The chamber 5 has a horizontal cross section very much greater than that of the b'oreil; and preferably'the body of liquid I8 is comparatively light, such asoil. This oil may be appropriately colored, to assist visibility.

Whenthe syste rnII ,is to be tested,.the leak detector 14 connected in place, the body of liquid is being then in the bottom of the hollow boss 30. Thencornpressed airor other gas thedium'is p uh iped into the system. Pressure exerted on the top surface of the body or the liquid [8 drives the liquidup to theposition illustrated in Fig. 4. Here thejliquid is representedby the reference characterZE, having an upper liquid level 26 and alower liquid le /e121. This lower Iiquidlevel is considerably above the bottom of thetube l, It balanced in the position shown 1 by theoppo'sed pressures exerted on the opposite levels 26 and '27. The position of the lower level 2 is sensitive to the pressure existing inthe system i. This is clear'from the following considerations. I I

,fWhen' gas pressure is "applied to the top level of the liquidfili injtheposition of Fig. 1, the liq- 'uid isforceo; upwardly through the'tube I6 into the: glass tube 1', and at least partially into the .onamoor' This continues until there is an equilibrium between the pressure exerted on the I upperan'd lower surfaces 26 and 21 ofthe liquid ston iii. .Thus the pressure exerted on. the l evel 27 otthe' liquid is balanced by the gravity head represented by the height of the liquid piston, plus thep'ressure of the air confined in the space of chamber 5 ab ove the level Upon pumping up the system, therefore, the observer notes the position of the lower level 21. If there are no leaks in thesystem, this lower 7 stays constant. should there'be 1eaks,"how ever the lower level gradually drops and if the leak is quitera'pid, then the body of liquid quite: rapidly drops down into 'the chamber I l.

Since the bore 8 of tube T is very small, even at considerable lowering of the lower level 2'! corresponds to a very small change in pressure, because the total volume of liquid passing out of chamber 5 is nevertheless small. This corresponds to a small change in volume of the gas 5 trapped in chamber 5, which in turn corresponds to a very small change in the gas pressure above the level 26. Accordingly when the pressure exerted on the lower level 21 is reduced, even very slightly, there is a considerable lowering of the level 21. It may be readily proved that if the volume of the gas or air trapped in chamber 5 is 1.41 cubic inches (as in an actual embodiment), and if the bore 8 is .080 inch in diameter, then a reduction of pressure from 24.7 pounds to 24.612 pounds corresponds to a drop in the oil level of .1 inch. This is readily noted; although the differencein the pressures is'o'nly .083 pound.

Whatis claimed is: r 4 1. In a'leak detector for a system of connected Iluid'passages, means forming an upper closed liquid chamber, means forming a downwardly directed transparent conduit communicating with the chamber. and having a cross section for the .dowr'iwa'rdflow of liquid that is muchsrnaller th that of the chamber, means forming a lower passageway adapted to be connected to the'siystern under test, and in communication with the lower en'ol of the conduit, and a liquid piston adapted to operate partly in the conduit and partly in the upper chamber,

2. Ina leak'dietector for a system of connected ffhudpassagesfmeans forming an upper closed liquid chamber, means forming a downwardly directed j transparent conduit communicating with the chamber and having a cross section for the downward flow of liquid that iemuch smaller 'thanthat of the chambenmeans for connecting the lower end of the conduit to the system under test, and a liquid of light specific gravity form- :ing a piston operating so that its lower level is above the bottom of the conduit, said liquid extending into the upper chamber. 3. In ajleakidetector'fora system of connected jiuid passages, means forming an upper closed .liquid'chambenjme'ans forming a downwardly di- .rected transparent conduit communicating with the chamber. and having a cross section for the downward now of liquidthat is r'nuch smaller 7 than that of the chamber, means forming a lower 5 passagewayfadapted tobeconnected to the sys. te munder testyand in" communication with the lower end'ofthe conduit, and a body of liquid having a lower level thatis above the bottom of the conduit, said body extending at least partly mto'theupper chamber, whereby variations in the lower level of the liquid in the conduit correspond to variations in the pressure operating upon the top "and bottom levels of theliquid. I a. In a leak detector for a system of connected 6O fluidpassa'gfi .means forming achamber closed ept for an elong'atedftra nsparent conduit of all cro'ss secftionthat extends from the chamliql i means iii the conduit for providing a cl urejfo'r the chamber, said liquid moans'extendihgintothe chamber beyond the conduit, the lower I end thereof being exposed in the conduit, Iand'me'ans for subjecting'that area of the liquid means which isexposed in the conduit to the pressure of the fluid passages.

1 GUSTAV 

